// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/audio/win/avrt_wrapper_win.h"

#include "base/logging.h"
#include "base/macros.h"

namespace avrt {

// Function pointers
typedef BOOL(WINAPI* AvRevertMmThreadCharacteristicsFn)(HANDLE);
typedef HANDLE(WINAPI* AvSetMmThreadCharacteristicsFn)(LPCWSTR, LPDWORD);
typedef BOOL(WINAPI* AvSetMmThreadPriorityFn)(HANDLE, AVRT_PRIORITY);

HMODULE g_avrt = NULL;
AvRevertMmThreadCharacteristicsFn g_revert_mm_thread_characteristics = NULL;
AvSetMmThreadCharacteristicsFn g_set_mm_thread_characteristics = NULL;
AvSetMmThreadPriorityFn g_set_mm_thread_priority = NULL;

bool Initialize()
{
    if (!g_set_mm_thread_priority) {
        // The avrt.dll is available on Windows Vista and later.
        wchar_t path[MAX_PATH] = { 0 };
        ExpandEnvironmentStrings(L"%WINDIR%\\system32\\avrt.dll", path,
            arraysize(path));
        g_avrt = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
        if (!g_avrt)
            return false;

        g_revert_mm_thread_characteristics = reinterpret_cast<AvRevertMmThreadCharacteristicsFn>(
            GetProcAddress(g_avrt, "AvRevertMmThreadCharacteristics"));
        g_set_mm_thread_characteristics = reinterpret_cast<AvSetMmThreadCharacteristicsFn>(
            GetProcAddress(g_avrt, "AvSetMmThreadCharacteristicsW"));
        g_set_mm_thread_priority = reinterpret_cast<AvSetMmThreadPriorityFn>(
            GetProcAddress(g_avrt, "AvSetMmThreadPriority"));
    }

    return (g_avrt && g_revert_mm_thread_characteristics && g_set_mm_thread_characteristics && g_set_mm_thread_priority);
}

bool AvRevertMmThreadCharacteristics(HANDLE avrt_handle)
{
    DCHECK(g_revert_mm_thread_characteristics);
    return (g_revert_mm_thread_characteristics && g_revert_mm_thread_characteristics(avrt_handle));
}

HANDLE AvSetMmThreadCharacteristics(const wchar_t* task_name,
    DWORD* task_index)
{
    DCHECK(g_set_mm_thread_characteristics);
    return (g_set_mm_thread_characteristics ? g_set_mm_thread_characteristics(task_name, task_index) : NULL);
}

bool AvSetMmThreadPriority(HANDLE avrt_handle, AVRT_PRIORITY priority)
{
    DCHECK(g_set_mm_thread_priority);
    return (g_set_mm_thread_priority && g_set_mm_thread_priority(avrt_handle, priority));
}

} // namespace avrt
